The Brunswick Naval Air Station occupies 3,094 acres in the Town of Brunswick. It is located south of the Androscoggin River, between Brunswick and Bath, Maine, south of Route 1, and between Routes 24 and 123. Among the site areas, three were used primarily for landfilling the station's household, office, and other wastes. The landfills were used from 1945 to 1979. Other areas were reported to have releases occur or have been used for disposal of various acids, caustics, solvents and building materials including asbestos, and used for fire training purposes. Approximately 3,000 people live on the base within a mile of the site areas. An elementary school, a college, and a hospital are located within 1 mile of the western base boundary. Area surface water is used for recreation, irrigation, and commercial fishing.

Due to past disposal practices, the soil and groundwater on a portion of the base is contaminated with volatile organic compounds (VOCs). Harpswell Cove, a valuable, commercial fishery located downgradient of the site, is subject to potential groundwater contamination. Ingestion of contaminated groundwater may pose health risks, however it has been determined through investigations that no current drinking water supplies are threatened.

This base was addressed in three phases: initial removal actions; long-term remedial actions focusing on cleanup of specific areas of contamination; and long-term monitoring, and operation and maintenance. Cleanup actions have been completed on several site areas. Four of the completed site areas have begun long-term monitoring to assess the effectiveness of cleanup actions.

In 1994, at a former pesticide storage area over 1,000 cubic yards of pesticide contaminated soil were removed and transported for off-site incineration. At the former fire training site, contaminated soil and buried drums were excavated and transported off the base for treatment and disposal.

Construction of the site remedy which included a 12-acre double barrier landfill cap, a 2220 foot slurry wall, and a groundwater extraction and treatment was completed in 1996. Groundwater, surface water, and sediment continue to be monitored. In November 1997, after two and one half years of groundwater extraction, the extraction wells within the landfill were shutdown because, based on water level data, it appeared that the groundwater table had dropped below a significant amount of the landfill waste. Groundwater level has remained steady. Monitoring of groundwater, surface water, sediment, leachate, and leachate seep sediment continues on a biannual basis.

Eastern Plume

An interim remedy was selected in July 1992. The remedy's goal is hydraulic containment of contaminated groundwater, which will prevent further migration and potential discharge into the Harpswell Cove estuary. Groundwater extraction and treatment began in May 1995. Contaminated groundwater is pretreated for metals and volatile organic contaminants are treated using UV/oxidation. Long-term monitoring of groundwater began in early 1995. An additional extraction well was added in 1998 to extract a hot spot of contaminated groundwater near MW-311. A final ROD was signed in February 1998, selecting containment of contaminated groundwater and restoration of the aquifer. The long term monitoring plan was revised in 1998. It reduced monitoring to biannually and improved the monitoring well network. Extraction well EW5 was replaced with a deep screened extraction well to remove more contaminants in 2000. Improving the treatment system by replacing the UV oxidation process with an air stripper and carbon polisher were studied in 1999 and implemented by an Explanation of Significant Differences to the ROD in 2000. This improves contaminant removal efficiency from 50% to >90%. The ESD also specified switching the plant effluent discharge to an infiltration gallery. Institutional controls to prevent use and exposure to the groundwater while it is being cleaned up were formally added as a remedy component by the ESD.
A supplemental ground water investigation was completed in 2010 to delineate the extent of 1,4-dioxane within the Eastern Plume Site. Data from this and other previous investigations formed the basis for issuance of a 2010 Explanation of Significant Differences to the current cleanup strategy. The significant difference to the current remedy is the modification of the ex-situ treatment process used to remove Eastern Plume contaminants, including 1,4-dioxane, from extracted ground water. A patented oxidation treatment unit that uses ozone and hydrogen peroxide to destroy the contaminants was selected. Extracted ground water now passes through the oxidation treatment unit followed by air stripping and granular activated carbon treatment. The air stripping process may be bypassed in the future should treatment system performance data indicate that the oxidation and granular activated carbon processes are sufficient to meet performance standards.

Site 8 Perimeter Road Landfill

Expressing opposition to the original containment remedy, the local community played a role in the final remedy selection for this area. Finalized in mid-1993, the remedy for the site involved excavation of contaminated soils and transportation of the soils to Sites 1 and 3 where it was used as part of the landfill cap. No land use restrictions are necessary at this area since all materials were removed. Cleanup activities, including site restoration, were completed in the fall of 1995.

Sites 5 & 6

Finalized in mid-1993, the selected remedy for these sites involved removal of soil,construction debris, and asbestos-containing materials, encapsulation of asbestos-containing pipes in two layers of polyethylene, and transportation of all materials to Sites 1 and 3 where it was used as part of the landfill cap. No land use restrictions are necessary at this area as all materials were removed. Cleanup activities were completed in mid-1995.

Neptune Drive Disposal Area (Site 9)

An interim remedy, selected in the fall of 1994, involves long-term monitoring of groundwater, surface water and sediments. Long term monitoring began in early 1995. Additional source investigations that were conducted in the fall of 1995 did not identify a particular source of the volatile organic groundwater contamination. A final ROD was signed in 1999 selecting Natural Attenuation, Long Term Monitoring, Institutional Controls, and Five Year Reviews as the final remedy at Site 9. In 2000 this remedy was initiated and documented in an EPA Interim Remedial Action Report. During 2005, Navy removed the barracks at the site and started to remove the underlaying landfill. Excavation continues through 2007 with additional investigation planned to determine the full extent of the landfill.

Sites 2, Orion Street Landfill South

Approximately two acres in extent, the landfill at Site 2 was reportedly the primary base landfill from 1945 to 1955. Currently, the site is overgrown by a grove of conifers. A ROD was signed in September 1998. Due to minimal risks, the remedy selected in the ROD was long term monitoring and institutional controls. Visible metal debris was removed in 1999 and the landfill slope was stabilized and regraded. Institutional Controls were implemented in 1999,long term monitoringstarted in 2000 and continues on a biannual basis.

Sites 4, 11, and 13

At Site 11, the former fire training, a removal action to address drums, contaminated soil, and an underground storage tank was conducted in 1994. Underground storage tanks at Site 4 and 13 have been removed. Based on these actions, no further source control action is proposed for these sites. A Final ROD was signed in February 1998 which identifies no further source control action at Sites 4,11, And 13; a contingent action if Building 584 at Site 4 is removed; and continued groundwater extraction and treatment to contain the Eastern Plume and restore the aquifer. Additional investigative work to delineate plume migration pathways in the vicinity of site 11 was performed in 2001, 2003, 2004 and was continued to 2005. No bedrock contamination was found.

Sites 7, 12 and 17

Investigations have been completed at Site 7. At Site 7 a limited removal was performed in 2001 in an attempt to remove the source of cadmium in groundwater slightly above the MCL. Groundwater sampling after the removal indicated the removal was not successful since cadmium was still detected in groundwater above the MCL. A Record of Decision implementing a limited action remedy including groundwater monitoring and institutional controls was signed in September 2002. Long term groundwater monitoring will begin in 2005.
Site 12, the explosives ordnance disposal and training area, was closed as part of the BRAC process. The Navy began surface munitions clearance activities in 2010 and completed work in 2011. A plan to evaluate the potential presence of munition items in a pond located on site will be developed in 2012. A remedial investigation will be conducted in 2012 to evaluate any potential impacts past ordnance disposal operations may have had on site soil ground water, surface water and sediment quality.

At Site 17, the Navy performed a limited removal action during the 1990s. This resulted in a decrease in associated site risk posed by contaminated soil and ground water, however, further characterization of these media was determined to be necessary. A draft remedial investigation report was completed in 2009. Initial results indicated unacceptable human health risks from site soil exposure. The Navy completed additional focused soil removals in 2009 and 2010 to address these risks. The draft remedial investigation was then updated in 2011 to reflect current site conditions. Based on these post-removal action results, calculated risks to human health and the environment were determined to be acceptable for unrestricted land use. A 2011 Record of Decision documented that no further remedial action was necessary for Site 17 soils. Ground water quality at Site 17 continues to be evaluated and will be addressed in a future Record of Decision.

Site-wide

The EPA produced a "Preliminary Close-Out Report" in September 2002 to document that the milestone of Construction Completion was reached with the signing of the Site 7 ROD. This milestone means that a Record of Decision has been signed for all OUs/sites and that all ROD's requiring it have a constructed remedy placed into operation.

Enforcement Highlights

In October 1990, the Navy and the EPA agreed on their cleanup responsibilities under an Interagency Agreement (IAG). The IAG later was amended to include the State of Maine as a party to the cleanup. Brunswick Naval Air Station is participating in the Installation Restoration Program, a specially funded program established by the Department of Defense (DOD) in 1978 to identify, investigate and control the migration of hazardous contaminants at military and other DOD facilities. In 1990, the first EPA Technical Assistance Grant (TAG) was awarded to a local community group called Brunswick Area Citizens for a Safe Environment. Follow-on grants have been awarded to continue TAG support. Throughout the entire process, there has been excellent public participation, especially from the TAG recipient.

Since the Brunswick Naval Air station site was placed on the National Priorities List, most of the base's old underground storage tanks have been removed and replaced. Through other environmental programs, the Navy is cleaning up contamination resulting from the former fuel tank farm and taking steps to improve the quality of stormwater discharges on the base. The majority of direct contact threats on the base have been eliminated through cleanup actions completed in 1995. Long-term monitoring on some areas of the base have begun, and data evaluated yearly. The first and second Five Year Review of all sites was performed in 2000 and 2005. It found that all remedies implemented were protective of human health and the environment, but it recommended several modifications to increase remedy effectiveness. These have been partially completed as of 2007.

Since the Brunswick Naval Air station site was placed on the National Priorities List (NPL), direct contact threats on the base have been eliminated through cleanup actions completed by 1995. Through other environmental programs, the base's old underground storage tanks have been removed and replaced. The Navy is cleaning up contamination resulting from the former fuel tank farm and has taken steps to improve the quality of stormwater discharges on the base. Operation of the groundwater pump and treatment system for the Eastern Plume continues and long-term monitoring is in progress and data evaluated yearly. The first and second Five Year Review of all sites, which was performed in 2000 and 2005, found that all remedies implemented were protective of human health and the environment and recommended several modifications to increase remedy effectiveness. These modifications included installing new deep extraction wells, and a confirmation of plume and institutional control boundaries. A phase of the field work to confirm plume boundaries was performed in 2001 and follow-on phases are planned to be completed in 2008.